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The goal of this program was to study the feasibility of operating a Detroit Diesel Series 149 engine at high speeds using a Coal-Water-Slurry (CWS) fuel. The CWS-fueled 149 engine is proposed for the mine-haul off-highway truck and work boat marine markets. Economic analysis studies indicate that, for these markets, the use of CWS fuel could have sufficient operating cost savings, depending upon the future diesel fuel price, emission control system capital and operating costs, and maintenance and overhaul costs. A major portion of the maintenance costs is expected to be due to lower life and higher cost of the CWS injectors. Injection and combustion systems were specially designed for CWS, and were installed in one cylinder of a Detroit Diesel 8V-149TI engine for testing. The objective was to achieve engine operation for sustained periods at speeds up to 1,900 rpm with reasonable fuel economy and coal burnout rate. A computer simulation predicted autoignition of coal fuel at 1,900 rpm would require an average droplet size of 18 microns and 19:1 compression ratio, so the injection system, and pistons were designed accordingly. The injection system was capable of supplying the required volume of CWS/injection with a duration of approximately 25more » crank angle degrees and peak pressures on the order of 100 mpa. In addition to the high compression ratio, the combustion system also utilized hot residual gases in the cylinder, warm inlet air admission and ceramic insulated engine components to enhance combustion. Autoignition of CWS fuel was achieved at 1900 rpm, at loads ranging from 20--80 percent of the rated load of diesel-fuel powered cylinders. Limited emissions data indicates coal burnout rates in excess of 99 percent. NO{sub x} levels were significantly lower, while unburned hydrocarbon levels were higher for the CWS fueled cylinder than for corresponding diesel-fuel powered cylinders.« less |
